A matrix-addressable device is an electronic device containing a group of cells addressed through electrodes arranged in a multi-dimensional matrix. For example, in a two-dimensional matrix-addressable device, a set of first electrodes typically extend in one direction. A set of second electrodes extend above the first electrodes in another (often perpendicular) direction so that the second electrodes cross the first electrodes. The cell locations are defined at the crossing points of the two sets of electrodes. Each cell is addressed through an appropriate one of first electrodes and an appropriate one of the second electrodes.
There are many types of matrix-addressable devices. One type is matrix-addressable sensors. Another type is flat-panel displays in which the display thickness is considerably less than the display length and width. A flat-panel CRT display is one example of a flat-panel display. Other examples include liquid-crystal, electroluminescent, plasma, electrochromic, and electrophoretic displays.
One problem in manufacturing generally flat matrix-addressable devices is that the yield of good devices is inevitably less than 100%. If one picture element ("pixel") is defective in a flat-panel display, the entire display is defective. A lower device yield results in an economic loss. Accordingly, an important objective in fabricating matrix-addressable devices is to increase the manufacturing yield, especially when the devices are being fabricated on a volume-production scale.
Various techniques have been considered for increasing the manufacturing yield of matrix-addressable devices. One technique is to provide a matrix-addressable device with redundant (or back-up) components. Holmberg et al, U.S. Pat. No. 4,820,222, discloses how redundant pixel components are introduced into a flat-panel CRT display. Each pixel in Holmberg et al basically consists of multiple subpixels. The failure of one subpixel in any pixel of the flat-panel display of Holmberg et al generally does not cause the entire display to be defective provided that at least one other subpixel in the same pixel is good. The manufacturing yield is thereby raised.
Unfortunately, providing a matrix-addressable display with redundant pixels is disadvantageous for a number of reasons. In applications where the area occupied by a pixel must fall within certain dimensional constraints, the size of each of the primary pixel components (i.e., the pixel components which would be present in the absence of the redundant components) must be reduced in order to enable each pair of primary and redundant components to be created in the same area otherwise occupied only by a primary pixel component. This can degrade the operational performance of the primary pixel components. Also, the complexity is increased, thereby reducing the reliability. It is desirable to increase the yield in manufacturing matrix-addressable devices without incurring a loss in device performance or reliability.